Hydrocarbons and other fluids are often contained within sub-terrain formations at elevated pressures. Wells drilled into these formations allow the elevated pressure within the formation to force the fluids to the surface. However, in low pressure formations, or when the formation pressure has diminished, the formation pressure may be insufficient to force the fluids to the surface. In these cases, a pump can be installed to provide the required pressure to produce the fluids.
A positive displacement pump, such as a piston pump, can be used in a well to create the pressure necessary to continue pumping fluid from low pressure formations. A drawback of conventional piston pumps is that if something blocks or obstructs the fluid flow, such as a shut valve or a frozen line, the pump will continue to increase pressure until the pump breaks or another system failure such as a leak occurs.